I had no trouble early on level wise, but I think I was really exploring all the opening islands, finishing everything I could find. I did not do any noticeboard missions until I was forced to around level 28, where the main mission suddenly jumped 5 levels above me.
My advice would be to pick a few noticeboard missions that suit your Kassandra (if you don't want to murder Spartan leaders, then don't), you definitely need a few (unfortunately) to supplement the other means of gaining XP.
It's the biggest problem in an otherwise superb game, if they can find a way to balance it for those that don't want to do everything, it would even better.

Let us know how you get on, Dragon's Dogma is genuinely my favourite game of all time.
I was going to say it has the best blocking of any game, then I remembered it also has the best spell-casting of any game, too. The best nights... It's basically the best.
I can highly recommend @Nathan Wind's pawn, The Groob to accompany you on your journey, he'll add a bit of comedy. Careful though, he's afeared of water.

This is another character triumph for CPDR, what they've done with Meve is fantastic. I was so impressed with how they brought (Blood and Wine spoiler)
in Witcher 3, and they've matched it here, with much less book material to work with.
Thronebreaker is quite excellent, presumably it'll get a little more exposure when the Red Dead rush has died down, and it hits consoles.
I was afraid I wouldn't like it aspects of it, I was never a fan of the seasonal challenges in Gwent which are essentially the puzzles in this, thankfully they are much improved. The regular (3 round) battles are great, too, and really give you a chance to mess around with your custom deck/army.
Presentation and voice acting are great, the choice and consequence is handled really well and more important than all of that, it tells an excellent story. I'm really hoping it ends with a particular epic encounter from the books
If I had to mention one niggle, it's the amount of resource collecting you do, it's been fun exploring the locations first time through but I fear it may put me off an (immediate) replay. I think a system where you receive a trickle of resources periodically would be better, but it definitely doesn't ruin the experience.

If you're dabbling in a bit of all activities, main story, side missions, naval combat, exploration, I think you're ok. But I can definitely see those looking to mainline the story really struggling, there are some big jumps in level requirements.
I go pretty all-in on these games, I don't mark a waypoint and sprint around the map ticking things off like some, but I do like to explore and I do enjoy most of the optional activities. It's a shame that people that do play differently and just want to follow the story may struggle though, because from what i've played so far, that would be a very satisfying journey.

Flippin' hell, the Mykonos questline is absolutely superb.
If they could find a way to condense this game into it's story missions and fantastic side quests, I think there would be more people willing to give it a go, but the sheer volume of additional content is surely putting some off. The best parts are really really good.

I don't think it is that different to previous games in terms of how much stealth and assassinating there is, you only ever really took out key targets with an assassination in the earlier games, and then were forced into melee combat. You can still use the environment to move around undetected, and height to scout out locations.
I tend to approach most objectives with stealth, and it works. Sure there are times when something goes wrong and you get forced in to melee. The difference here is the melee combat is FUN and I don't actually mind when all hell breaks loose. Things have changed, but not as much as being made out, and for me it is definitely for the better. I certainly don't miss those follow missions along really telegraphed routes, or blending into mindlessly wandering crowds, this all feels much more natural.